Asteroid miners are not any better than dwarves in fantasy. Always digging too deep. This map is based on the concept of a "space dungeon" and finding something ancient and alien locked inside a remote asteroid, Cthonus.
This 50x100 square map is divided into three sections and comes with four alternate versions with and without a grid, and as separate map sections.:
1) The main level with a loading/hangar bay, engineering facilities, a control center, and crew quarters.
2) The bottom level of the mines connected to the previous area by a mining elevator. There can be any number of other mining levels before this, but they can be just generic mining levels with nothing of value or interest in them.
3) The Vault of Cthonus. An ancient vault built by a vanished alien civilization. There is something horrible growing and mutating inside the breached vault.